51^ ' SPECIMENS OF -SIR J. HALl's EXPERIMENTS. 



Specimens of specimen for lost, till some time in July 1804, when employ«4 



results of bodies j^^ examining these results, in order to show them in the Royal 

 exposed to =■ . "^ 



strong heat Society of Edinburgh, a mass of the carbonate broke in two, 



fi^on^V^Si^"^^^' ^^"^ exhibited the fracture now before us, nearly in as good a 

 Jaires Hall. state as it was originally. I immediately enclosed it in a glass 

 tube, and sealed it up with wax ; so that I have hopes of preserv- 

 ing it ; and it still continues intire, though now sealed up for a 

 year and a half. Number 18, likewise from pounded chalk, is 

 perfectly fresh and intire, though made more than two years 

 ago; it shows some beautiful clear crystals of spar in parallel 

 pla-tes, but they are so small as to require the use of a glass. 



Numbers 19, 20, and 21, shew examples of fusion and actiorj 

 on the tubes. In Number 19, a shell is finely united to some 

 pounded chalk. In Number 20, the mass, originally ofpoundecj 

 chalk, is sinking upon itself, and acting at the same time upon 

 , the tube ; the fracture of the carbonate, in its pure parts, shew- 

 ing brilliant facettes of crystallization. In Number 21, the 

 carbonate in a state like the last ; the compound of porcelain 

 and carbonate shewing its liquidity by penetrating the tube, so 

 as to form a distinct view of '4 dark colour, and then spreading 

 on its outside to a considerable extent, terminating with the 

 black line, alluded to in the account of the experiments. 



Numbers 22, 23, and 24, give, proofs of intire fusion. In 

 Number 22, we see two porcelain tubes, enclosed for preserva-? 

 tion in a glass tube ; the end attached to the little wooden cup 

 must be held downwards, to show the position in which the ex- 

 periment was made. The innermost porcelain tube stands 

 v.'ith its muzzle upwards, and the outermost covers it in the 

 inverse position. The carbonate was contained in the inner 

 tahc during the action of heat : the barrel failed suddenly, and 

 the carbonate has boiled over the lips of the inner tube, run-^ 

 ning down, as here appears, almost to^its bottom : thus prov- 

 ing, that immediately previous to the failure of the apparatus, 

 fhe carbonate had been in a liquid state. Number 23, two 

 mascs of carbonate welded together in a complete stale of froth, 

 The substance shining, and semitransparcnt. 



Number 24, two separate masses exposed together to heat; 

 one from pounded chalk, nov.' in a state quite like the last, the 

 other put in as a lump of chalk dressed flat at both ends, and a 

 letter cut at each end (as done in many of tlie experiments). 



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